Are XP bonuses cumulative?

Because the ability on the icon is a replacement, the player is brought to suspect that the ability also replaces, which is not the case.
They are meant to stack.

There needs to be some consistency with the desciptions of these abilties so that this question doesn't keep popping up on the forums.

The tooltips are very confusing, I get descriptions like:

Food production: +2 -> +2

Research bonus: +50% -> +50%

Sometimes a building gives an impression its completion has no effect whatsoever. 

+XP stacks.

The very existence of these traits is my pet peeve about the game.

It may be communicated in a confusing way, but there is some sense behind those indicators. If the number stays the same nothing changes when you build the improvement on that term. Almost all improvements follow a tree of their own and when you upgrade to the next level the indicator shows you that the preceding building already raised the number but the following is not. It will increase something else.

I really like this approach. You get to see before and after states. If they're the same, it means the building in question isn't changing that aspect.

Color coding could be a nice addition though. I think they've tried it, but have inconsistencies.

Green = Increase from previous

Red = Decrease from previous

Yellow = Stays the same

Naturally, this can become confusing with items that are BETTER as they decrease (like unrest)...so that color code could be a little more dynamic:

Green = Better state from previous

Red = Worse state from previous

Yelllow = Stays the same

I agree that this is a nice feature. Once you get used to it, you look for the green numbers...

What I am missing, though, is knowing what that particular building is an upgrade from.

Yeah I've only finished one game of LH, but I thought it was a bit odd that these traits exist. I'm not seeing much reason to take anything else. Indeed, the heroes of AI that I made to surrender all had taken these abilities.

I suspect the place for the mechanic is map size. I could see where XP would need to be higher on a small map versus a large one. But why not just make that a factor of map size and not hero traits?

I wondered this myself. I know skills like lethal have the same type of description but it is a replacement and not a stacking effect.

lethal is not a replacement. none of the skills in the trait tree are. they are all cumulative (please correct me if that rule is not consistently applied - i can't think of a single exception right now)

It all depends on the files XML data. Most of the traits and abilities are additive and not replacement values. The fact is that the upgrades are not replacing the previous skill they are combining with the previous skill. This is why when it is +1 +2 +3, it really is +1 to +3 total to +6 total. They are much more interesting (benificial might be a better term) traits than people first preceive.

I could have sworn that at one time they were replacements. Was it ever the case they were, or did I just never notice that?

yeah i agree the way the information is presented is a bit confusing for a new player. but after taking a look at the mage or commander trees (or the general tree of all classes) it should be quite obvious that the traits stack. wouldn't make any sense at all to have trait lines like Prodigy 1-3, Evoker 1-4, Tactician 1-3 or even the general trait Quickness 1+2 since each rank of those traits has the same amount. could be presented in a more newbie friendly fashion (for example, with a tooltip that indicates "Potential 2 - increases XP gain by 20% for a total of 35%" or something along that line.

i started playing FE a short time after release, and it's always been like that since then. it's definitely never been any different in LH. no idea if it was different in the FE beta

I really wish they would do this!

These should all be removed from the game.  What a lame ass level choice, let alone 3 or 4 choices.  Take them all out and change leveling so we level more and faster.  Make the choices something fun and not something lame.

Though I agree, this is a totally different topic from the OP.

Having defended potential all through FE, I am finally ready to admit that this trait tree should be retired.  The bonuses should be innate considering how freaking painfully slow it is to level champions.  I'm still fine with knowledge for mages, however, as that class is even more level-dependent than the other 4.

yeah i agree that the traits should probably be removed. they aren't useful. in fact, i consider them a trap. a player who doesn't know the game very well may think they are useful and pick that nonsense instread of using the actual traits of their path. which leads to totally useless heroes in the important early part of the game where heroes are the key factor for a successful game. by crippling them with potential, you might just as well not have any heroes at all at that stage. later on, when the potential finally pays off, you don't really need the heroes any more, anyway. at that point, you can just as well use trained troops without worrying about heroes once you get some mid tier weaponry and armor going and have enough production and income to build and maintain a few armies of those troops.

What you just described has been the biggest problem I have with LH at the moment, though I disagree with your conclusion re: potential.  I wouldn't even say that they're the key factor in early game, unless you have a fire/death apprentice, and their time of usefulness is quickly outpaced by trained troops' tech levels.  Heroes absolutely must get a huge injection of XP gain in order to stay relevant throughout the entire course of the game.

I would tend to agree that the Potential traits are something of a trap, unless you intend to get a champion to very high levels (for the game, anyways).

A little chart I made (note that it was made using level experience values from FE; I haven't checked to see if these have changed, but I don't believe they have):

Traits     Break-Even Level

P1                20

P2                18

P3                17

K                  12

KP1              16

KP2              17

KP3              17

P1/P2/P3 are Potential I/II/III respectively, K is Knowledge, and KP1/KP2/KP3 are Knowledge and Potential I/II/III. The break-even level is the level that your champion would normally be without experience-boosting traits by the time your champion with the experience-boosting traits has gained as many extra levels as you put into the experience-boosting traits, assuming that you took the experience-boosting traits as soon as they became available, in the order which provides the greatest bonus. All of this also assumes that there are no level requirements on any of the experience-boosting traits beyond picking up prerequisite traits. I.e., you can and do take Potential I at level 3, Potential II at level 4, and Potential III at level 5, or Knowledge at level 3, Potential I at level 4, Potential II at level 5, and Potential III at level 6 (or at least as far up those paths as each list goes). For mage champions, or for non-mage champions who gain significant bonuses with each level, these traits are probably worthwhile. For champions whose utility mostly comes from their traits, these traits represent a questionable investment of your level-up traits.

The other thing that I don't think was addressed earlier in the thread is that the bonuses are additive, not multiplicative, so Potential I and Knowledge together provide a 40% bonus to experience gain rather than a 43.75% bonus to experience gain.

I believe that if multiple champions in an army have traits in the Trainer line, the experience bonus gets added together (so two champions each with Trainer I provide a 20% bonus, rather than just the 10% bonus). However, if you stack Trainer champions like this, you are still suffering a net loss of experience (Yay! +80% experience from two champions with Trainer IV! But I need to divide across two champions, so it's more like 90% of normal experience - which is still far better than the 50% of normal you'd get otherwise - but you need to have two commander champions of at least level 9 who took three leadership traits and four trainer traits).

Henchmen/Scions can also provide the trainer traits and don't count as heroes when dividing xp.

Potential-focused heroes - getting ready for future that may never come

How about that - as a motto?  

Agreed entirely. Drop them and just make everyone level at an appropriate pace. I tend to treat them as compulsory picks which means there are three levels of boredom while you take them. Or alternatively if the game balance is such that they aren't worth while (ie early LH when heroes were gaining so little XP that you wouldn't reach the break even point) then you don't pick them at all. Either way I don't think they are an interesting or fun feature.

Very interesting.  But how exactly did you get those numbers?

care to elaborate? i'm not sure i understand your point. 

let me give some examples for hero builds i like to use, that don't need potential or a very high level to dramatically change the game

- tank defender: grab defense 1&2 and you can use him as a tank. works like a charm against all those low level melee troops; not so useful against ranged units, though. just give him a few spearmen for damage; in battle, move the defender forward, tank 3-4 units, move your spears to flanking positions and swarm the enemy one by one. no casualties. bonus points if you play kingdom an have life 1 on one of your champs (regen to full after battle - grind mites, bandits, wolves etc. non stop). at higher levels (8-10 or something) he's by far the best option for dealing with dragons, golems, titans and other nasty stuff. doesn't really need more than 8 levels to tank. delaying those 8 levels for potential is just dumb, since he's a real force especially in the early game. later you can use tained tank units for this role. they aren't as good as a defender, but good enough to get the job done.

- life mage: pick up life 2 (if you don't have that yet), compassion, then life 3 (at level 5) for shrink, life 4 at level 7. at level 4 and 6 you can start picking prodigy. once you reach "savant" (should be at level 9) you can kick out AoE heals with no cast time and shrink nasty stuff (like dragons). chance of success is good, since you have 30 spell mastery from prodigy. at that point, he doesn't really need more level ups. can grab some water magic (if available) to have even more debuffs to weaken strong mobs; or progress into the summoning tree, or grab some of the utility spells that branch off the prodigy line

- death mage: go for greater necromancy, then death 3, prodigy 1-3, savant. requires about 8-9 levels. gives you access to skeleton hordes and allows you to cripple your opponents reliably with instant cast wither and mass curse.

- commander: get accuracy 1, command, then accuracy 2-4, tactician 1-3 and battle cry. if you have good support spellbooks available, you can grab some of those spells before finishing the main commander tree (air is great for a commander - mostly buff spells, so his low spell mastery is irrelevant). prodigy might be useful for him, but only if you think you need both, battle cry and whatever high level spells he may have access to. if he doesn't have useful magic, potential is a waste on him - go stragiht for battle cry (which you should be able unlock at level 10 or 11)

- warrior: get lethal 1-3; at level 5, he's already at 15 attack plus whatever his weapons adds. then go for axeman or spearman for extra AoE killing power, or head for bladerush, or grab the extra HP and chain armor proficiency and the swordsman line to use him as an offtank (he won't main tank really tough stuff, but unlike the defender, his buffed up counterattacks can actually kill )

none of those builds require a very high level to be very viable. in fact, they are a lot less useful if you delay the early level ups for "potential" picks. let's face it - once you get to mid tier weapons, you can win the game without using your heroes. by delaying their devlopment, you sacrifice all the wonderful heroic deeds they might have performed during the most crucial time of the game (early game, obviously) to be a bit better at a stage of the game where they aren't really required any more.